a blog to answer medical questions in fiction writing

Head Injury and Medically Induced Coma

Question:

My victim was deliberately run over by a mountain biker. Skull fracture, internal injuries broken bones. Would the victim be put into a medically induced coma and what drugs are used. How do doctors determine when to bring someone out of a coma?

Answer:

The short answer is…maybe (if necessary to control intracranial pressure (ICP)), propofol or pentobarbital, and it depends (probably ICP coming under control). (helpful, right?) Scroll to the bottom for the short summary, or read on to understand what’s going on.

Traumatic brain injury (TBI) might occur with a skull fracture, with outcome ranging from complete recovery to death, and everything in between. Best if they are managed at a Trauma Center or at least a hospital with neurosurgical services.

Patients with TBI frequently have other injuries that complicate care, but here I’ll focus on TBI itself.

Prehospital

Glasgow Coma Scale (GCS): This would be performed early on and is a measure of brain function. It includes three areas:

Eye opening (spontaneous (4) down to none (1))

Best verbal response (not looking for a great pun, but oriented (5) down to no response (1))

Best motor response (obeys commands (6) down to no movement (1))

Yes, teenagers can still get a 6. They just have to squeeze your hand…but preferably not pull your finger.

GCS 15 is max; 13 is mild brain injury, <9 is severe. This is something the paramedics would report over the radio to the receiving hospital.

If the score is <9, the victim would be intubated (breathing tube in the windpipe) and the paramedic would be squeezing a breathing bag. They would also place an IV (intravenous) catheter and give fluids to maintain blood pressure. The GCS would be determined every few minutes to look for deterioration.

Emergency Room

They would follow the Advanced Trauma Life Support (ATLS) protocol (ask if you want more info), and scan the head (CT scan) to assess the brain. The big fear is “elevated ICP.”

Intracranial pressure (ICP) is the pressure inside the cranium (skull). In adults, the skull is solid, with just a few holes (e.g., eyes, and where the spinal cord departs for points south). Inside that solid skull is the brain, blood vessels, and another fluid (CSF: cerebrospinal fluid).

When something else takes up space (e.g. blood that has escaped), the skull can’t swell. Instead, the pressure inside the skull rises which can (1) reduce blood flow and (2) cause the brain to get squeezed toward the hole for the spinal cord. Unfortunately, the part of the brain most likely to get squished (herniate) through the hole is in charge of the most basic life functions (like breathing). So herniation is quite lethal. Incidentally, we look at pupils because the nerves that control them are in that same area.

So…if the CT showed a “hematoma” or blood collection, beneath the skull, it would likely be surgically drained immediately. For a skull fracture, as in your case, surgical treatment would depend on whether it was open (scalp open as well) and how deeply depressed the skull was.

So you could get away without surgery if you want. But they would at least have “minor” surgery with the placement of a pressure catheter into the brain to monitor ICP. The patient would be on a ventilator with a breathing tube, and would be receiving medications to maintain his blood pressure and try to minimize his ICP. He would be sedated, potentially to the point of a medically induced coma.

Medically Induced Coma

(you thought I’d never get there)

When nothing else works, the brain might be put to sleep. The goal is to minimize the oxygen needs of the brain, and thus the need for blood flow. Either pentobarbital or propofol would be used. The latter had become more popular, then a “new” disorder cropped up called “propofol infusion syndrome” which can be lethal and has reduced enthusiasm for long term use of the drug.

These patients have continuous EEG monitoring (electrodes on the head) to make sure we are sufficiently depressing their brain activity.

When to wake them up depends on why they were placed in the coma in the first place, but usually it’s based on the ICP, so when the ICP stays down, it’s time to stop the sedation and see how the patient wakes up.

Summary

Of course much more could be said. From a fiction standpoint, realism would come from the initial evaluation, the GCS, intubation and ventilation. A CT scan with results, the choice to induce a coma, with plenty of discussion from the physician to the family about the low likelihood of a return to prior functioning, but that it wasn’t time yet to talk about withdrawing care. Then a GRADUAL awakening when the sedation is discontinued – much faster with propofol than with pentobarbital. By the way, more realism, the propofol is a white milky liquid going into their IV.

Also plenty of opportunity for additional tension with complications like infections, other injuries, discussion of a “DNR” (Do Not Resuscitate) since the outcome if the victim’s heart stops is truly dismal. Oh the possibilities….

A teen is an adult in this respect. The skull is composed of several plates that are incompletely fused to allow the head to squish a bit on the way out of the birth canal. These close by about 18 months of age.